Extend (Reduce/Contract/Skrink) Function for Oracle

Recently I was looking at some cadastral data with a view to working out how to polygonize the linestrings. The data contains this sort of boundary understood anomaly. To be able to able to form intersections between the cadastral boundaries and the road frontage I need to be “extend” the linestrings along the direction ofRead More

A Short Biography

Simon Greener has some 25 years IT experience, including 2 years developing database mainframe applications and 3 years researching geospatial solutions at Telstra (research created Censis’s spatial division), 2 years conducting GIS research at University of Tasmania, 5 years as Director, Technical Solutions at Salamanca Software (including designing first Whitepages web database and application forRead More


The following is a list of customers to whom I have provided services. 1Spatial, Cambridge, England Australia Post, Melbourne, Australia Australian Bureau of Statistics, Canberra, Australia Barwon Water, Geelong, Victoria Brisbane City Council, Brisbane, Queensland British Geological Service, England Danish Police Department of Primary Industries, Parks, Water and Environment, Corporate Information Technology (CIT), Hobart, TasmaniaRead More

Vectorization: Exploding a linestring or polygon into individual vectors in PostGIS

I find having a vectorising function in my database kit-bag almost indispensable in my work. I have written and revised my Oracle PL/SQL functions that do this many times over the years and so, when I first started using PostGIS, I decided to learn how to program in PL/pgSQL by implementing something familiar: a GetVector()Read More

How to apply spatial constraints to PostGIS tables

This article was written before TypeMod was introduced eg Geometry(Polygon,28355) As I have pointed out in other blog articles, spatial data quality should not engender either/or solutions when building business applications. That is, if I can only create points for parcel centroids that fall within land parcels, then I don’t just build the rule inRead More

To Constrain or Not to Constrain: There should be NO Question

In my consulting travels I, like many other database-loving specialists, find databases with little (a Primary Key, perhaps) or no constraints being applied to the data model managed by a relational database (which may be Oracle, SQL Server, PostgreSQL, MySQL etc). I finalised a report for a Government Department here in Australia recently where thisRead More